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Parasitology Proficiency Testing Program

BBPO CRITIQUE FOR 03 October 2005

The purpose of the New York State Proficiency Testing Program in the category of Parasitology Blood Borne Parasites is to monitor the performance of applicant laboratories in detecting and identifying parasites on blood films.

SAMPLE PREPARATION AND QUALITY CONTROL

All slides used in this test were prepared and stained by a commercial source. Numerous samples of each test specimen were selected at random by the Parasitology Unit of the David Axelrod Institute for Public Health, and were checked to confirm their contents. Extensive quality control tests were also conducted by the supplying vendor and a detailed quality control report was submitted to the New York State Parasitology Laboratory for inspection and verification. Samples were authenticated by 80% of participating laboratories and/or referee laboratories.

ANSWER KEY

SAMPLE	CORRECT ANSWERS	POINTS
06B-F	Plasmodium malariae	20
06B-G	NO PARASITES SEEN	20
06B-H	Trypanosoma brucei*	20
06B-I	NO PARASITES SEEN	20
06B-J	Plasmodium vivax*	20

TOTAL POSSIBLE POINTS 100

* Unauthenticated

SAMPLE 06B-F

RESULTS OF PARTICIPATING LABS

ORGANISM	NUMBER REPORTED	PERCENT REPORTED	STATUS
Plasmodium malariae	13/13	100	Correct

QUALITY CONTROL

Participating laboratories agreed that Plasmodium malariae was the correct response (100%). Quality control examination of 4% of this sample showed infected erythrocytes in every 2-3 oil emersion fields. The infected cells are not enlarged and no stippling was observed. The predominant stage seen was the mature trophozoite.

DIAGNOSTIC CHARACTERISTICS

Plasmodium malariae is the least common species of plasmodium to infect humans and is sporadic in distribution. It tends to infect older red blood cells and so the parasitemia is often low. The ring stage is short lived so it is not usually seen. The most common stages seen are mature trophozoites and schizonts. The infected cells are not enlarged and may actually be smaller than uninfected cells. There is no stippling. The trophozoites are not amoeboid and often appear as compact rounded or band forms. The schizonts contain 6-12 merozoites usually arranged in a rosette although they may be in an irregular cluster.

SAMPLE 06B-G

RESULTS OF PARTICIPATING LABS

ORGANISM	NUMBER REPORTED	PERCENT REPORTED	STATUS
NO PARASITES SEEN	13/13	100	Correct

QUALITY CONTROL

Participating laboratories agreed that No Parasites Seen was the correct response (100%). Quality control examination of 4% of this sample showed erythrocytes of normal size and staining characteristics. Normal blood elements are present and exhibit typical staining characteristics. No inclusions are present.

SAMPLE 06B-H

RESULTS OF PARTICIPATING LABS

ORGANISM	NUMBER REPORTED	PERCENT REPORTED	STATUS
Trypanosoma brucei	06/13	46	Unauthenticated
Trypanosoma cruzi	07/13	54	No Penalty

QUALITY CONTROL

Participating laboratories failed to agree that Trypanosoma brucei was the correct response (46%). Quality control examination of 4% of this sample showed parasites in every oil emersion field. The erythrocytes are normal to slightly smaller than normal in size and no stippling is present. The parasites are long and undulating with a very small kinetoplast at the blunt posterior end.

DIAGNOSTIC CHARACTERISTICS

Trypanosoma brucei gambiense is the causative agent of African sleeping sickness. It is limited to the tse tse fly endemic area of Central Africa where it has caused serious economic and social problems. Trypomastigotes are detected in the blood on thick and thin giemsa stained smears. They measure 14-33 microns long and in some cases the undulating membrane and flagellum may be seen. The nucleus is located in the middle of the organism and the kinetoplast from which the flagellum arises is located at the blunt posterior end. On a giemsa stained smear the cytoplasm will stain blue and the nucleus and kinetoplast will stain red or purple. Trypomastigotes of T. cruzi are similar but are generally shorter, have a 3-5X larger, more prominent kinetoplast at a pointed posterior end and assume a C or U shape.

SAMPLE 06B-I

RESULTS OF PARTICIPATING LABS

ORGANISM	NUMBER REPORTED	PERCENT REPORTED	STATUS
No Parasites Seen	13/13	100	Correct

QUALITY CONTROL

Participating laboratories agreed that No Parasites Seen was the correct response (100%). Quality control examination of 4% of this sample showed erythrocytes of normal size and staining characteristics. Normal blood elements are present and exhibit typical staining characteristics. No inclusions are present.

SAMPLE 06B-J

RESULTS OF PARTICIPATING LABS

ORGANISM	NUMBER REPORTED	PERCENT REPORTED	STATUS
Plasmodium vivax	08/13	62	Unauthenticated
Plasmodium ovale	05/13	38	No Penalty

QUALITY CONTROL

Participating laboratories failed to agree that Plasmodium vivax was the correct response (62%). Quality control examination of 4% of this sample showed parasites in nearly every oil emersion field. Cells are enlarged and Schüffner's stippling is present. The parasites are amoeboid and the predominant stages seen are trophozoites and gametocytes. Pigment was scattered and fine.

DIAGNOSTIC CHARACTERISTICS

Plasmodium vivax is the most common species of malaria to infect humans. It may account for as much as 80% of all malaria cases. It also has the widest distribution. Infected red cells are usually enlarged and stain paler than uninfected ones. They may also contain Schüffner's dots. The trophozoites are generally amoeboid and have a large chromatin. Occasionally cells will contain more than one parasite. Mature schizonts contain 12-24 merozoites. The top two images show Gametocytes of P. vivax and P. ovale. In P. vivax they are round and fill the entire cell unlike P. ovale which are smaller and don't usually fill the entire RBC. Pigment is fine and scattered in P. vivax and much coarser in P. ovale. The next two images show trophozoites of P. vivax and P. ovale In P. vivax the parasite is amoeboid and so the cell is very distorted. When pigment is present it is fine. In P. ovale the trophozoite is much more compact and the pigment is coarse.

OCTOBER DISTRIBUTION OF SCORES

SCORE	NO. OF LABS	PERCENT
100	13	93
0	1	07

 

GRADING

The answer key was derived from the response of all participating laboratories as per CLIA Regulations, Part 493, Subpart I, Section 493.917. These regulations can be viewed at www.phppo.cdc.gov. These regulations state that 80% or more of participating laboratories or referee laboratories must identify the parasite for it to be correct. Similarly, less than 20% of the participating laboratories or referees finding parasites or ova is an incorrect response. Organisms reported by 20-80% of the participating laboratories or referees are "Unauthenticated", and are not considered for grading.

Each sample has a maximum value of 20 points. Credit is given according to the formula:

Number of correct responses by lab # Correct Parasites Present + # Lab's Incorrect Answers

X 100

IMPORTANT REMINDERS

The next Parasitology Proficiency Test is scheduled for February 06, 2006. You are responsible for notifying us before February 13, 2006 if you do not receive your test. Proficiency test results must be postmarked by February 21, 2006 or you will receive a zero. These requirements are clearly stated in your NYS Proficiency Testing Handbook provided by the NYS Clinical Laboratory Evaluation Program or can be accessed via the internet at www.wadsworth.org/labcert/clep/ProgramGuide/WebGuide.pdf.

NEWS AND NOTES

Policy changes made by the Clinical Laboratory Evaluation Program now allow for the CQ holder for a particular category to sign the attestation statement instead of the Laboratory Director. Starting with the February 05, 2001 test event we will now accept Director's and/or CQ holder's signatures on the attestation statement.

The Clinical Parasitology Lab of the NYSDOH offers two mailing kits for the submission of specimens. One kit contains vials of PVA and Formalin and the other does not. These kits can be ordered by calling 518-474-4175 and requesting kit DOH-2117. Please be sure to specify whether you need preservatives or not. Remember that the NYS Parasitology Lab only accepts specimens preserved in appropriate fixatives for the test requested.

Two one day Malaria Workshops are scheduled for April 11 and 12, 2006. These workshops will be presented in conjunction with the NLTN and will be held at Long Island University C.W. Post Campus in Brookville, NY. Registration forms will be sent to all permitted laboratories. For further information call 800-536-NLTN or visit NLTN web site.

Web site questions or comments or to request a different file format (pdf.,doc.,wpd.) contact:
E-mail: Parasit@wadsworth.org.